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Hierarchical spin-orbital polarization of a giant Rashba system.

Bawden L, Riley JM, Kim CH, Sankar R, Monkman EJ, Shai DE, Wei HI, Lochocki EB, Wells JW, Meevasana W, Kim TK, Hoesch M, Ohtsubo Y, Le Fèvre P, Fennie CJ, Shen KM, Chou F, King PD - Sci Adv (2015)

Bottom Line: The Rashba effect is one of the most striking manifestations of spin-orbit coupling in solids and provides a cornerstone for the burgeoning field of semiconductor spintronics.Combining polarization-dependent and resonant angle-resolved photoemission measurements with density functional theory calculations, we show that the two "spin-split" branches of the model giant Rashba system BiTeI additionally develop disparate orbital textures, each of which is coupled to a distinct spin configuration.This necessitates a reinterpretation of spin splitting in Rashba-like systems and opens new possibilities for controlling spin polarization through the orbital sector.

View Article: PubMed Central - PubMed

Affiliation: SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, Fife KY16 9SS, UK.

ABSTRACT
The Rashba effect is one of the most striking manifestations of spin-orbit coupling in solids and provides a cornerstone for the burgeoning field of semiconductor spintronics. It is typically assumed to manifest as a momentum-dependent splitting of a single initially spin-degenerate band into two branches with opposite spin polarization. Combining polarization-dependent and resonant angle-resolved photoemission measurements with density functional theory calculations, we show that the two "spin-split" branches of the model giant Rashba system BiTeI additionally develop disparate orbital textures, each of which is coupled to a distinct spin configuration. This necessitates a reinterpretation of spin splitting in Rashba-like systems and opens new possibilities for controlling spin polarization through the orbital sector.

No MeSH data available.


Related in: MedlinePlus

Surface electronic structure of BiTeI.(A) ARPES measurements of the Fermi surface and near-EF band dispersions measured (hν = 52 eV, p-polarization) from the Te-terminated surface of BiTeI. (B) A lack of inversion symmetry of the bulk crystal structure together with strong spin-orbit coupling mediates a large Rashba-like spin splitting. Additionally, the polar nature of the Te-terminated surface induces a strong downward band bending, causing a ladder of Rashba-split subband states to emerge in the near-surface quantum well. (C) These are clearly resolved in measurements of the dispersion along Γ–M. The conventional spin texture associated with such Rashba splitting is shown schematically by colored arrows, with the spin expected to lie predominantly in the surface plane.
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Figure 1: Surface electronic structure of BiTeI.(A) ARPES measurements of the Fermi surface and near-EF band dispersions measured (hν = 52 eV, p-polarization) from the Te-terminated surface of BiTeI. (B) A lack of inversion symmetry of the bulk crystal structure together with strong spin-orbit coupling mediates a large Rashba-like spin splitting. Additionally, the polar nature of the Te-terminated surface induces a strong downward band bending, causing a ladder of Rashba-split subband states to emerge in the near-surface quantum well. (C) These are clearly resolved in measurements of the dispersion along Γ–M. The conventional spin texture associated with such Rashba splitting is shown schematically by colored arrows, with the spin expected to lie predominantly in the surface plane.

Mentions: A giant Rashba-like spin splitting has recently been discovered for bulk conduction and valence band states of bismuth tellurohalide semiconductors (13–15). Arising because of a combination of bulk inversion asymmetry (Fig. 1B), strong atomic spin-orbit coupling, and a negative crystal field splitting of the valence bands (14), Rashba parameters have been uncovered that are among the highest of any known materials, together with a counter-rotating chiral Fermi surface spin texture (13, 16). Exploiting element- and orbital-selective angle-resolved photoemission (ARPES), we show that a complex interplay between atomic, orbital, and spin degrees of freedom significantly enriches this picture. We expect our findings to be broadly applicable across other strong spin-orbit Rashba systems.


Hierarchical spin-orbital polarization of a giant Rashba system.

Bawden L, Riley JM, Kim CH, Sankar R, Monkman EJ, Shai DE, Wei HI, Lochocki EB, Wells JW, Meevasana W, Kim TK, Hoesch M, Ohtsubo Y, Le Fèvre P, Fennie CJ, Shen KM, Chou F, King PD - Sci Adv (2015)

Surface electronic structure of BiTeI.(A) ARPES measurements of the Fermi surface and near-EF band dispersions measured (hν = 52 eV, p-polarization) from the Te-terminated surface of BiTeI. (B) A lack of inversion symmetry of the bulk crystal structure together with strong spin-orbit coupling mediates a large Rashba-like spin splitting. Additionally, the polar nature of the Te-terminated surface induces a strong downward band bending, causing a ladder of Rashba-split subband states to emerge in the near-surface quantum well. (C) These are clearly resolved in measurements of the dispersion along Γ–M. The conventional spin texture associated with such Rashba splitting is shown schematically by colored arrows, with the spin expected to lie predominantly in the surface plane.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4643772&req=5

Figure 1: Surface electronic structure of BiTeI.(A) ARPES measurements of the Fermi surface and near-EF band dispersions measured (hν = 52 eV, p-polarization) from the Te-terminated surface of BiTeI. (B) A lack of inversion symmetry of the bulk crystal structure together with strong spin-orbit coupling mediates a large Rashba-like spin splitting. Additionally, the polar nature of the Te-terminated surface induces a strong downward band bending, causing a ladder of Rashba-split subband states to emerge in the near-surface quantum well. (C) These are clearly resolved in measurements of the dispersion along Γ–M. The conventional spin texture associated with such Rashba splitting is shown schematically by colored arrows, with the spin expected to lie predominantly in the surface plane.
Mentions: A giant Rashba-like spin splitting has recently been discovered for bulk conduction and valence band states of bismuth tellurohalide semiconductors (13–15). Arising because of a combination of bulk inversion asymmetry (Fig. 1B), strong atomic spin-orbit coupling, and a negative crystal field splitting of the valence bands (14), Rashba parameters have been uncovered that are among the highest of any known materials, together with a counter-rotating chiral Fermi surface spin texture (13, 16). Exploiting element- and orbital-selective angle-resolved photoemission (ARPES), we show that a complex interplay between atomic, orbital, and spin degrees of freedom significantly enriches this picture. We expect our findings to be broadly applicable across other strong spin-orbit Rashba systems.

Bottom Line: The Rashba effect is one of the most striking manifestations of spin-orbit coupling in solids and provides a cornerstone for the burgeoning field of semiconductor spintronics.Combining polarization-dependent and resonant angle-resolved photoemission measurements with density functional theory calculations, we show that the two "spin-split" branches of the model giant Rashba system BiTeI additionally develop disparate orbital textures, each of which is coupled to a distinct spin configuration.This necessitates a reinterpretation of spin splitting in Rashba-like systems and opens new possibilities for controlling spin polarization through the orbital sector.

View Article: PubMed Central - PubMed

Affiliation: SUPA, School of Physics and Astronomy, University of St. Andrews, St. Andrews, Fife KY16 9SS, UK.

ABSTRACT
The Rashba effect is one of the most striking manifestations of spin-orbit coupling in solids and provides a cornerstone for the burgeoning field of semiconductor spintronics. It is typically assumed to manifest as a momentum-dependent splitting of a single initially spin-degenerate band into two branches with opposite spin polarization. Combining polarization-dependent and resonant angle-resolved photoemission measurements with density functional theory calculations, we show that the two "spin-split" branches of the model giant Rashba system BiTeI additionally develop disparate orbital textures, each of which is coupled to a distinct spin configuration. This necessitates a reinterpretation of spin splitting in Rashba-like systems and opens new possibilities for controlling spin polarization through the orbital sector.

No MeSH data available.


Related in: MedlinePlus